1. Field of the Invention
This invention relates to adhesive compositions suitable for laminating polyvinyl chloride to wood or other substrates. The adhesives are blends of polyvinyl chloride and two different ethylene copolymers. The adhesive compositions are useful for preparing laminates which are suitable for outdoor use.
2. Description of Related Art
Adhesives are used in a wide variety of fields. For some applications the requirements of the adhesive may be very demanding. Not only must the composition provide good initial adhesion, but the adhesive bond may be subject to extremes of temperature or environment. Such is the case for adhesives used in outdoor building applications.
In the building industry, siding may be a laminate structure which requires an adhesive to make that laminate. That adhesive should be readily applied to the laminate components, it must adhere well to each of the layers of the laminate and the bonding must withstand the rigors of outdoor use. Common among siding materials are wood, metals and polyvinyl chloride.
Various materials are known for use as thermoplastic adhesives which may be applied in the melt as a molten fluid. If the viscosity of the melt is suitable for film extrusion, and cooled extruded film is stiff enough to handle, these copolymers may be adapted to films for laminating adhesives.
Various ethylene copolymers are well known as hot-melt thermoplastic adhesives. Ethylene/alkyl acrylate/carbon monoxide copolymers have been described for use as adhesives for use with a wide variety of substrates in PCT publication WO91/18043.
Ethylene vinyl acetate copolymers have long been known for use as hot-melt adhesives.
Ethylene butyl acrylate copolymers for use as hot-melt adhesives have been described in U.S. Pat. No. 4,816,306.
Ethylene/alkyl acrylate or vinyl acetate/carbon monoxide terpolymers have been disclosed for use especially as plasticizers for PVC in U.S. Pat. No. 3,780,140. Blends with PVC can be used as limp or rigid films. The terpolymers are disclosed alternately as being blendable with a large number of other materials, including epoxy resins.
None of the references disclose the particular three component combination of this invention, nor is there even any suggestion that blends of PVC with any ethylene copolymer or copolymers would be suitable as laminating adhesives.
There is a need for an adhesive material which provides good adhesion between polyvinyl chloride sheeting and various substrates, particularly wood, and which maintains that adhesion under outdoor weathering conditions.